Vladimir Putin will speak to Donald Trump by telephone on Saturday in their first conversation since the US president’s inauguration, as top Trump advisor Kellyanne Conway told Fox News that removing US sanctions on Russia is “under consideration”.

Diplomats and politicians in many world capitals will be watching the call with unease, as Trump’s positive rhetoric on Russia threatens to disrupt the western consensus of keeping pressure on Moscow over its intervention in Ukraine. Many US senators, including from the Republican party, are also deeply concerned about the prospect of a major rapprochement with Moscow.

He has hinted he could look at removing sanctions on Russia, although at a press conference with Theresa May on Friday said it was “very early to be talking about that”. Previously he has suggested the US and Russia could work together in Syria, where Russia is allied with the Syrian president, Bashar al-Assad.

Asked on Fox and Friends whether sanctions imposed by the Obama administration were on the table during Saturday’s phone call, Conway said “all of that is under consideration”.

Putin’s spokesman, Dmitry Peskov, said the Russian president would congratulate Trump on taking office and would launch a discussion on the current bilateral relationship. He said it was unlikely there would be specific agreements reached in the initial call.

“This is the first telephone contact since President Trump took office, so one should hardly expect that this phone call will involve substantive discussions across the whole range of issues. We’ll see, let’s be patient,” Peskov said.

Peskov said he was unaware of any plans to lift the sanctions.

Conway, a White House senior aide, told This Morning on CBS that Trump and Putin were likely to discuss efforts to combat terrorism.

“I assume they will discuss, in the interests of their respective countries, how to come together and work together on issues where you can find common ground and where these two nations could maybe defeat radical Islamic terrorism,” she said.

Trump was also due to speak with the German chancellor, Angela Merkel, on Saturday, a source in Berlin told Reuters, in a call likely to focus on Russia policy.

Earlier this month, Trumptweeted: “Both countries will, perhaps, work together to solve some of the many great and pressing problems and issues of the WORLD!”

Last July, he said at a press conference: “Wouldn’t it be nice if we actually got along with people? Wouldn’t it be nice if we actually got along, as an example, with Russia? I am all for it.”

Trump’s warm feelings towards Russia became one of the biggest talking points in the aftermath of his surprise election victory, with US intelligence agencies releasing a report commissioned by Barack Obama which drew the conclusion that Russia had interfered in the election with the aim of getting Trump elected.

The dossier was compiled by former MI6 agent Christopher Steele as opposition research on Trump, but he was so alarmed by what he found that he passed it to the FBI.

The claims in the dossier, that Trump had been compromised by the Russians during trips to Moscow, and that members of his entourage had links with Russian intelligence, have not been corroborated. However, US intelligence agencies felt strongly enough about the reliability of Steele as a source to follow up on them.

Russia has vehemently denied any interference in the electoral process, and Putin laughed off claims Russia had compromised Trump, saying he doubted Trump would use prostitutes. He said those behind the dossier were “worse than prostitutes”.

Rumours have swirled in Washington in the past days that Trump could be readying a swift end to US sanctions on Russia. There are currently several sets of sanctions, not all of which Trump could remove by executive order. The Magnitsky Act, which targets corrupt officials, was passed by Congress and will not be simple to repeal. However, the several rounds of sanctions over Russian intervention in east Ukraine and the annexation of Crimea could be undone with a stroke of Trump’s pen.

Should Washington end sanctions, it will put EU governments in a difficult position, as they will not want to be seen as softening the line against Moscow, but at the same time European businesses will not appreciate the competitive advantages that US business would receive from a unilateral cancellation of sanctions.

Finding consensus on sanctions, which are agreed by unanimity among the EU’s 28 member states, has become harder and harder. Italy, Greece and Hungary, have criticised the sanctions regime for damaging their own economies, while creating tensions with Moscow.

A spokeswoman for the EU foreign policy chief, Federica Mogherini, declined to comment on “rumours” that sanctions would be lifted by the US. “Our restrictive measures were adopted here by 28 member states and that remains to be the case.”

EU sources said it was too early to say what would happen, with one hitting back at suggestions EU unity would crumble. “We decide on our sanctions, not the Americans,” the source, adding that the measures were coordinated through the G7, which includes Canada and Japan.

“This is a very theoretical debate and a lot of things might change before July,” the source added. “The one thing that is certain is that everyone will watch this [US] decision very closely - if there is one.”

There has been a cautious optimism in Moscow in recent weeks about the prospect of a new era of Russia-US relations in which Moscow is not lectured for human rights abuses, and is given free reign to act as it pleases in neighbouring countries. State television has given Trump largely positive coverage, a sharp departure from the anti-US rhetoric of recent years. A recent survey found that just 4% of Russians thought Trump would be a bad president.